Method and apparatus for cleaning a surface

Abstract: A cleaning method and apparatus that provides lubrication to a secondary detoning roll (112) in a cleaner brush system, thus reducing cleaning failures. The toner particles removed from the first detoning roll (111) are transported to the second detoning roll (112). This allows lubrication of the second detoning roll (112) and reduces the wear problem of the second detoning roll (112) due to lack of lubrication.

Description: This invention relates generally to an electrophotographic printing device, and more particularly, a lubricating system in the cleaner apparatus that lubricates a detoning roll. In an electrophotographic application such as xerography, a charge retentive surface (e.g. photoconductor, photoreceptor or imaging surface) is electrostatically charged, and exposed to a light pattern of an original image to be reproduced to selectively discharge the surface in accordance therewith. The resulting pattern of charged and discharged areas on that surface form an electrostatic charge pattern (an electrostatic latent image) conforming to the original image. The latent image is developed by contacting it with a finely divided electrostatically attractable powder referred to as "toner". Toner is held on the image areas by the electrostatic charge on the surface. Thus, a toner image is produced in conformity with a light image of the original being reproduced. The toner image may then be transferred to a substrate (e.g. paper), and the image affixed to form a permanent record of the image to be reproduced. Subsequent to development, excess toner left on the charge retentive surface is cleaned from the surface. The process is well known, and useful, for light lens copying from an original or printing applications from electronically generated or stored originals such as with a raster output scanner (ROS) where a charge surface may be imagewise discharged in a variety of ways. Ion projection devices, where a charge is imagewise deposited on a charge retentive substrate, operates similarly. In a reproduction process ot the type as described above, it is inevitable that some residual toner will remain on the photoconductor surface after the toner image has been transferred to the sheet of support material (e.g. paper). It has been found that with such a process the forces holding some of the toner particles to the imaging surface are stronger than the transfer force and, therefore, some of the particles remain on the surface after transfer of the toner image. In addition to the residual toner, other particles, such as paper debris (i.e. Kaolin, fibers, clay), additives and plastic, are left behind on the surface after image transfer. (Hereinafter, the term "residual particles" encompasses residual toner and other residual debris remaining after image transfer.) The residual particles adhere firmly to the surface and must be removed prior to the next printing cycle to avoid it interfering with recording a new latent image thereon. A commercially successful mode of cleaning employed on automatic xerographic devices utilizes a brush with soft conductive fiber bristles or with insulative soft bristles which have suitable triboelectric characteristics. While the bristles are soft for the insulative brush, they provide sufficient mechanical force to dislodge residual toner particles from the charge retentive surface. In the case of the conductive brush, the brush is usually electrically biased to provide an electrostatic force for toner detachment from the charge retentive surface. Toner particles adhere to the fibers (i.e. bristles) of the brush after the charge retentive surface has been cleaned. The process of removing toner from these types of cleaner brushes can be accomplished in many ways. A common method for providing detoning of these electrostatic brushes is the use of detoning rolls. The particles removed from the brushes adhere to the detoning rolls and are then removed therefrom by scrapers. However, in this method a common problem is that the efficiency of the first detoning roll minimizes toner lubrication to the second detoning roll. This causes cleaning failures due to shorting of the brush bias to the detoning roll. A common compromise is made between performance and life, by slowing down the cleaner to reduce the wear rate and, shortening the scraper blade to reduce end wear of the detoning rolls. US-A-4,494,863 to Laing discloses a toner removal device for removing residual toner and debris from a charge retentive surface after transfer of toner images from the surface. This device is characterized by the use of a pair of detoning rolls, one for removing toner from a biased cleaner brush and the other for removing debris such as paper fibers and Kaolin from the brush. The rolls are electrically biased so that one of them attracts toner from the brush while the other one attracts debris. US-A-5 229 817 also describes a toner removal device utilizing a pair of detoning rolls rotatably engaging with one brush. JP-A-58 144 875 describes a toner removal device in which a first and second flicker bars engage with a first and second brush, respectively. According to the present invention there is provided a method and apparatus according to any one of the appended claims. Briefly stated, and in accordance with one embodiment of the present invention, there is provided a method for lubricating a second detoning roll, of a cleaning brush system, having a first and a second detoning roll, rotatingly engaged with a first brush and a second brush, respectively, the brushes being engaged with said surface, the method including: removing toner particles from said surface with the brushes; attracting the toner particles from the first brush with the first detoning roll; removing the toner particles from the first detoning roll; and moving said toner particles toward the second detoning roll to lubricate the second detoning roll. Pursuant to another embodiment of the present invention, there is provided a method for lubricating a second detoning roll, of a cleaning brush system, having a first and a second detoning roll, both rotatingly engaged with a brush and the brush being engaged with said surface, comprising: removing toner particles from said surface with the brush; attracting the toner particles from the brush with the first detoning roll; removing the toner particles from the first detoning roll; and moving the toner particles toward the second detoning roll to lubricate the second detoning roll. Pursuant to another embodiment of the present invention, there is provided an apparatus for cleaning toner particles from a moving surface, comprising: at least two brushes, a first brush and a second brush, each having a plurality of fibers extending outwardly therefrom; a housing, defining an open ended chamber, the brushes being mounted movably in the chamber of the housing with the fibers extending outwardly from the open end of the chamber of the housing in contact with the surface to remove the toner particles therefrom; detoning means, including a first detoning means and a second detoning means, to remove the toner particles from the fibers of said first and second brush respectively; and means for removing the toner particles from the first detoning means toward the second detoning means to lubricate said second detoning means Pursuant to another embodiment of the present invention, there is provided an apparatus for cleaning toner particles from a moving surface, comprising: a brush, having a plurality of fibers extending outwardly therefrom; a housing, defining an open ended chamber, the brush being mounted movably in the chamber of the housing with the fibers extending outwardly from the open end of the chamber of the housing in contact with the surface to remove the toner particles therefrom; detoning means, including a first detoning means and a second detoning means, to remove the toner particles removed from said surface from the fibers and means for removing the toner particles from the first detoning means toward the second detoning means to lubricate the second detoning means. The present invention will be described further, by way of example, with reference to the accompanying drawing illustrating a brush cleaning apparatus according to one embodiment of the present invention. Referring now to Figure 1, which shows a dual electrostatic brush cleaner incorporating the present invention in a vertical cleaner, where one brush 101 is located downstream from the second brush 102 in the direction of motion (indicated by arrow 12) of the photoreceptor belt 10. The toner particles 105 are removed from the photoreceptor 10 by the fibers of the brushes 101, 102. The cleaning brushes 101, 102 contact the photoreceptor 10 to remove the toner particles 105 therefrom. The brushes 101, 102 rotate in the "with" direction of motion of the photoreceptor 10. The direction of rotation of the cleaner brushes 101, 102 is indicated by the arrows 100, 120. Detoning rolls 111, 112 are used to remove the toner particles 105 picked up by the brush fibers 104, 106 The biased detoning rolls 111, 112 are located in adjacent proximity to the biased brushes 100, 120 to enable the detoning rolls 111, 112 to electrostatically remove the toner particles 105 from the brush fibers 104, 106. The detoning rolls 111, 112 rotate in the "with" direction of motion of their respective cleaner brushes 101, 102. The direction of rotation of the detoning rolls 111, 112 is indicated by the arrows 110, 140. The surface of the detoning rolls 111, 112 are cleaned of toner particles 105 by scraper blades 121, 122. The first cleaning brush 101 of the dual electrostatic brush cleaner removes approximately 90% of the toner 105 from the photoreceptor 10 with the second brush 102 cleaning the remaining toner particles 105. Prior to the present invention, a wear problem normally occurred on the second detoning roll 112 that was not found on the first detoning roll 111 due to the unequal distribution of toner 105 between the first brush 101 and the second brush 102. The scraper blade 122 and the respective anodized aluminum detoning roll 112 would wear at a much faster rate due to this decreased lubrication. The anodized coating would wear until the coating was thin enough that pin holes would occur on the surface of the detoning roll leading to decreased detoning efficiencies. Increased use lead to cleaning failures due to shorting of the brush bias to detoning roll. The present invention increases the reliability and life of a brush cleaner by reducing the failure level of the second detoning roll 112. This failure is due to a lack of toner lubrication between the second detoning roll 112 and the second scraper blade 122 which does not occur at the first detoning roll 111. The present invention uses the toner particles 105 cleaned from the first detoning roll 111, by the first scraper blade 121, on the second detoning roll 112. The toner particles 105 fall or are transported to the second detoning roll 112 thus, providing adequate lubrication for the second detoning roll 112. A baffle 130 is placed between the detoning rolls 111, 112 and the brushes 101, 102 to prevent the toner particles 105 removed from the first detoning roll 111 from falling onto the brushes 101, 102 in route to the second detoning roll 112 and to assist in guiding the toner particles 105 to the second detoning roll 112. The toner particles 105 removed from the second detoning roll 112 by the scraper 122 fall or are transported to a waste container (not shown). With a vertical cleaner (as shown in Figure 1), the toner 105 removed from the first detoning roll 111 can fall onto the second detoning roll 112 thus, providing adequate lubrication of the second detoning roll 112. A horizontal cleaner could use a paddle wheel to splash toner from the first detoning roll 111 onto the second detoning roll 112. This added lubrication from the first detoning roll 111 would resolve the problem of inadequate lubrication of the second detoning roll 112 without compromising cleaner performance. Another embodiment of the present invention, is the use of a single brush with two detoning rolls. As is true in the above-mentioned embodiments, the first detoning roll is biased differently than the second detoning roll. A baffle is present between the two detoning rolls to guide the toner removed from the first detoning roll to the second detoning roll. In recapitulation, the embodiment of the present invention in Figure 1 consists of a dual electrostatic brush cleaning system that directs the toner particles removed from a first detoning roll to a second detoning roll. This lubricates the second detoning blade thus, decreasing wear problems. These wear problems, in turn caused decreased detoning efficiencies such as shorting of the brush bias to the detoning roll. The present invention resolves detoning deficiencies without compromising performance and life as other methods have. It is, therefore, apparent that there has been provided in accordance with the present invention, a cleaning apparatus that lubricates a detoning roll that fully satisfies the aims and advantages hereinbefore set forth.

Claims: A method of cleaning a charge retentive surface of an electrophotographic printing device using a brush system having a first and a second detoning roll (111,112), rotatingly engaged with a first brush (101) and a second brush (102), respectively, the brushes (101,102) being engaged with said surface, the method including: removing toner particles from said surface with the brushes (101,102); attracting said toner particles from the first brush (101) with the first detoning roll (111); removing said toner particles from the first detoning roll (111); and being characterized by moving said toner particles toward the second detoning roll (112) to lubricate the second detoning roll (112). A method of cleaning a charge retentive surface of an electrophotographic printing device using a brush system having a first and a second detoning roll, (111,112), both rotatingly engaged with a brush (101), the brush (101) being engaged with said surface, comprising: removing toner particles from said surface with the brush (101); attracting said toner particles from the brush (101) with the first detoning roll (111); removing said toner particles from the first detoning roll (111); and being characterised by moving said toner particles toward the second detoning roll (112) to lubricate the second detoning roll (112). An apparatus for cleaning toner particles from a moving charge retentive surface of an electrophotographic printing device, including: at least two brushes (101,102), a first brush (101) and a second brush (102), each having a plurality of fibers extending outwardly therefrom; a housing, defining an open ended chamber, said brushes being mounted movably in the chamber of said housing with said fibers extending outwardly from the open end of the chamber of said housing in contact with said surface to remove the toner particles therefrom; detoning means including a first detoning means (111) and a second detoning means (112), to remove the toner particles from said fibers of said first and second brush respectively and being, characterised by means (121) for removing the toner particles from said first detoning means toward said second detoning means to lubricate said second detoning means. An apparatus as claimed in claim 3, further including a baffle (130), located between the first detoning means (111) and the second detoning means (112) to prevent the toner particles, removed from said first detoning means (111), from falling back onto the brushes (101,102). An apparatus as claimed in claim 4, wherein said baffle (130) guides the toner particles toward said second detoning means (112). An apparatus for cleaning toner particles from a moving charge retentive surface of an electrographic printing device, including: a brush (101), having a plurality of fibers extending outwardly therefrom; a housing, defining an open ended chamber, said brush being mounted movably in the chamber of said housing with said fibers extending outwardly from the open end of the chamber of said housing in contact with said surface to remove the toner particles therefrom; detoning means, including a first detoning means (111) and a second detoning means (112), to remove the toner particles removed from said surface from said fibers ; and being characterised by removing means (121) for removing the toner particles from said first detoning means (110) toward said second detoning means (140) to lubricate the second detoning means. An apparatus as claimed in claim 6, wherein said removing means (121) directs the toner particles toward said second detoning means. An apparatus as claimed in claim 7, further including means (130) for propelling the toner particles from said first detoning means (111) to said second detoning means (112). An apparatus as claimed in claim 8, wherein said propelling means (130) is located between said first detoning means (111) and said second detoning means (112).

Inventors: GERBASI DENNIS G, LANGE CLARK V, THAYER BRUCE E, GERBASI, DENNIS G., LANGE, CLARK V., THAYER, BRUCE E.
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1994
Main classification: G03G21
IPC codes: G03G21